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tracing/boot: Support multiple handlers for per-event histogram

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Support multiple handlers for per-event histogram in boot-time tracing.
Since the histogram can register multiple same handler-actions with
different parameters, this expands the syntax to support such cases.

With this update, the 'onmax', 'onchange' and 'onmatch' handler subkeys
under per-event histogram option will take a number subkeys optionally
as below. (see [.N])

ftrace.[instance.INSTANCE.]event.GROUP.EVENT.hist {
     onmax|onchange[.N] { var = <VAR>; <ACTION> [= <PARAM>] }
     onmatch[.N] { event = <EVENT>; <ACTION> [= <PARAM>] }
}

The 'N' must be a digit (or digit started word).

Thus user can add several handler-actions to the histogram,
for example,

ftrace.event.SOMEGROUP.SOMEEVENT.hist {
   keys = SOME_ID; lat = common_timestamp.usecs-$ts0
   onmatch.1 {
	event = GROUP1.STARTEVENT1
	trace = latency_event, SOME_ID, $lat
   }
   onmatch.2 {
	event = GROUP2.STARTEVENT2
	trace = latency_event, SOME_ID, $lat
   }
}

Then, it can trace the elapsed time from GROUP1.STARTEVENT1 to
SOMEGROUP.SOMEEVENT, and from GROUP2.STARTEVENT2 to
SOMEGROUP.SOMEEVENT with SOME_ID key.

Link: https://lkml.kernel.org/r/162856124905.203126.14913731908137885922.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu 2021-08-10 11:07:29 +09:00 committed by Steven Rostedt (VMware)
parent e66ed86ca6
commit 8993665abc
1 changed files with 35 additions and 8 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

43
kernel/trace/trace_boot.c
View file

@ -245,8 +245,9 @@ trace_boot_hist_add_array(struct xbc_node *hnode, char **bufp,
}
static int __init
trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp,
char *end, const char *param)
trace_boot_hist_add_one_handler(struct xbc_node *hnode, char **bufp,
char *end, const char *handler,
const char *param)
{
struct xbc_node *knode, *anode;
const char *p;
@ -259,7 +260,7 @@ trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp,
xbc_node_get_data(hnode), param);
return -EINVAL;
}
append_printf(bufp, end, ":%s(%s)", xbc_node_get_data(hnode), p);
append_printf(bufp, end, ":%s(%s)", handler, p);
/* Compose 'action' parameter */
knode = xbc_node_find_child(hnode, "trace");
@ -294,6 +295,32 @@ trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp,
return 0;
}
static int __init
trace_boot_hist_add_handlers(struct xbc_node *hnode, char **bufp,
char *end, const char *param)
{
struct xbc_node *node;
const char *p, *handler;
int ret;
handler = xbc_node_get_data(hnode);
xbc_node_for_each_subkey(hnode, node) {
p = xbc_node_get_data(node);
if (!isdigit(p[0]))
continue;
/* All digit started node should be instances. */
ret = trace_boot_hist_add_one_handler(node, bufp, end, handler, param);
if (ret < 0)
break;
}
if (xbc_node_find_child(hnode, param))
ret = trace_boot_hist_add_one_handler(hnode, bufp, end, handler, param);
return ret;
}
/*
* Histogram boottime tracing syntax.
*
@ -305,8 +332,8 @@ trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp,
* name = <HISTNAME>
* var { <VAR> = <EXPR> ... }
* pause|continue|clear
* onmax|onchange { var = <VAR>; <ACTION> [= <PARAM>] }
* onmatch { event = <EVENT>; <ACTION> [= <PARAM>] }
* onmax|onchange[.N] { var = <VAR>; <ACTION> [= <PARAM>] }
* onmatch[.N] { event = <EVENT>; <ACTION> [= <PARAM>] }
* filter = <FILTER>
* }
*
@ -368,13 +395,13 @@ trace_boot_compose_hist_cmd(struct xbc_node *hnode, char *buf, size_t size)
/* Histogram handler and actions */
node = xbc_node_find_child(hnode, "onmax");
if (node && trace_boot_hist_add_handler(node, &buf, end, "var") < 0)
if (node && trace_boot_hist_add_handlers(node, &buf, end, "var") < 0)
return -EINVAL;
node = xbc_node_find_child(hnode, "onchange");
if (node && trace_boot_hist_add_handler(node, &buf, end, "var") < 0)
if (node && trace_boot_hist_add_handlers(node, &buf, end, "var") < 0)
return -EINVAL;
node = xbc_node_find_child(hnode, "onmatch");
if (node && trace_boot_hist_add_handler(node, &buf, end, "event") < 0)
if (node && trace_boot_hist_add_handlers(node, &buf, end, "event") < 0)
return -EINVAL;
p = xbc_node_find_value(hnode, "filter", NULL);